Lenin Ocapmo Torres/European Pressphoto Agency Armed with iron rods and rocks, dozens of masked members of the teachers’ union in Guerrero State attacked the local offices of the four major political parties on Wednesday, smashing windows and overturning furniture. MEXICO CITY — One of President Enrique Peña Nieto’s signature efforts to shake up the country — a broad plan to overhaul the education system — has run into violent protests that underscore how difficult it may be to carry out, particularly in some volatile states with poor academic performance. Armed with iron rods and rocks, dozens of masked members of the teachers’ union in Guerrero State attacked the local offices of the four major political parties on Wednesday, smashing windows and overturning furniture. They also set fire to the office of the Institutional Revolutionary Party, or PRI, to which Mr. Peña Nieto belongs. On Thursday, in a further sign of the growing conflict over education changes, teachers marched…Read More